This invention pertains to precious metal vaporization.
In one of its more specific aspects, this invention relates to laminar refractory structures comprising a vapor barrier in combination with a precious metal.
The use of precious metals and their alloys is well known. Such metals, ordinarily including platinum, iridium, rhodium and the like, can be used in their pure forms, in combination with each other, as their oxides or combinations thereof. By precious metals as employed herein, are meant all such combinations of platinum, iridium and rhodium, in whatever form they may be employed. Frequently, such metals are employed under conditions which cause the migration of the precious metals from the principal body of the metal, itself.
One particularly suitable method for reducing precious metal vaporization from glass fiber forming apparatus, comprising platinum, is described and claimed in U.S. Pat. No. 3,859,070 issued Jan. 7, 1985 to Robert O. Slonaker, incorporated herein by reference. That process is directed to depositing a high density refractory material selected from the group consisting of magnesia, magnesium zirconate, zirconia, alumina, titania, chromia, aluminide, silicide, beryllides, borides and combinations thereof on the surface from which metal vaporization is to be reduced.
In an article by A. G. Knapton in PT. MT. RV. 23 (1979), "Ensuring the Most Advantageous Use of Platinum", a plurality of methods of reducing metallic migration are discussed.
There has now been discovered, however, a method which is a decided improvement of the foregoing methods.